Still executing afte die()?

I have a page called 404.php which is set as the 404 page in a .htaccess file. At the top of this file, it has this: if(strtolower($_SERVER['REQUEST_URI']) != $_SERVER['REQUEST_URI']){ header("Location: http://{$_SERVER['HTTP_HOST']}".strtolower($_SERVER['REQUEST_URI'])); die; } which redirects to the same page with a lowercase URL if there are any uppercase characters. After that, it inserts the 404 into the database for checking later. But, when I test it with something like PaGeTHATSHOULDBELOWERCASE.php, it redirects to pagethatshouldbelowercase.php but still inserts it into the database (with the uppercase page name) even though the redirected page is 404-free. What am I doing wrong? -- The above message is encrypted with double rot13 encoding. Any unauthorized attempt to decrypt it will be prosecuted to the full extent of the law.